1. Field of the Invention
This invention is in the field of removing excess oily based penetrant from the surface of a test piece to which the penetrant has been applied by means of a remover which includes a soap and then precipitating the soap and entrapped penetrant so that a clear supernatant liquid can be recovered either for purposes of recycle or for disposal.
2. Description of the Prior Art
The penetrant method of detecting surface discontinuities in a workpiece is well known. It involves applying a colored oily penetrant to the surface of the test piece and allowing sufficient dwell time for the penetrant to penetrate into any surface flaws. The penetrant may include a visible dye or a fluorescent dye. The excess penetrant is removed from the surface without substantial removal of the penetrant which has become entrapped in any flaws. Then, a developer is added either as a dry developer or as an aqueous or non-aqueous wet developer with or without intermediate drying of the surface. Finally, the surface is inspected for developed cover indications using ordinary light for visibly dyed penetrants, and "black" light if fluorescent penetrant is used.
There have also been numerous disclosures in the prior art of suitable liquid compositions for removing residual films of oil based color penetrants. One such disclosure appears in Mlot-Fijalkowski U.S. Pat. No. 3,558,882 assigned to the assignee of the present application. This patent describes a composition suitable for use as a remover and containing a liquid, water soluble, non-ionic surfactant, a water-immiscible aromatic hydrocarbon solvent having a KB value of at least 70 and a normally liquid, water miscible glycol-ether type of coupler.
While many types of prior art compositions can be used to effectively remove residual films of dyed penetrant from the surface of a test piece, there still remains the problem of disposing of the emulsified penetrant after its removal. This problem is particularly acute in the case of fluorescent penetrants since even a small amount of fluorescent dye in the rinse water is objectionable from the standpoint of reusing the rinse water or disposing of it into sewers.